Tufted carpet products bearing intricate patterns formed with a number of diverse colors are in high demand, particularly in industries such as the hospitality industry. U.S. Patent Publication No. 2009/0205547 to Hall et al. (“Hall”), the entirety of which is incorporated by reference, describes a tufting machine and related system for controlling the machine to form “free-flowing patterns.” Hall discloses a needle bar with a plurality of needles arranged across the bar. A yarn is associated with each needle. A backing material is fed under the needle bar, which is reciprocated to drive the needles through and out of the backing material to form loops of yarn in the backing material.
If the needle bar did not move laterally relative to the backing and operated as described above, the resulting product would simply consist of yarn loops extending in lines of a single color along the length of the backing material. To form a pattern with the yarn loops, it is necessary for the needle bar to shift laterally to vary the positioning of the different color yarn loops on the backing material to form a design. Hall teaches a control system that is programmed with the desired pattern information and that controls operation of the machine, including shifting of the needle bar, to create a desired pattern in the final tufted product.
Hall teaches thread-up of the needle bar with a repeating pattern of yarn colors across the needle bar. Thus, if the desired product is to have three different yarn colors (A, B, and C), those three colors would be threaded-up in the same order or sequence across the entire needle bar (i.e., ABCABCABC, etc.), as shown in FIG. 1. Hall teaches this same thread-up methodology of a repeating sequence or pattern of the colors regardless of the number of different color yarns desired to be used. See, e.g., FIGS. 6A-D. The control system must be told how many different color yarns are being used so that it can adjust the shifting of the needle bar and speed of tufting accordingly, as discussed below.
The appearance of a yarn loop on the face of a tufted product can be controlled by controlling the height of that yarn loop. Where a yarn loop of a particular color is not to be readily visible at a particular location, that yarn loop is formed or tufted “low” in that location so that the surrounding tufted loops of a different color that are to be visible are higher and thus more prominent visibly.
Hall controls the visibility of yarn loops on a tufted product by controlling the tension placed on the yarn to either “pull low or backrob” a yarn loop. According to applicants understanding, to “pull low” the yarn loop is first tufted to a tuft height and then partially pulled back through the backing material so as to form a lower height yarn loop extending from the backing material. To “backrob,” the yarn loop is first tufted and then pulled entirely from the face of the backing material. Some such loops are pulled entirely free of the backing, but others are left sufficiently embedded in the backing to “tack” the yarn in place on the backside of the backing. In this way, the backrobbed yarn loops are entirely invisible on the face side of the backing material.
A number of drawbacks result from the thread-up and tufting methodology taught by Hall. The implementation of pulling low or backrobbing results in a tufted product having a smaller amount of visible yarn on its face. To compensate for this, Hall teaches that the density of the yarn loops provided within a given length of the backing material must be increased. To achieve this, the machine must be operated at an increased or denser “stitch rate” (which Hall defines as the number of stitches per inch). Operation of the machine at a denser stitch rate slows the speed at which tufted fabric can be produced. For a given tufting bar reciprocation rate, the denser the stitch rate required, the slower the backing material can be fed through and tufted by the machine, and thus the slower the machine can be run.
This is only compounded by the number of different colors used to thread-up the machine. The more different colors used to form the pattern, the more the needle bar is required to shift and penetrate the backing material and the greater the distance the needle bar must shift to disperse the different colors across the backing material (i.e., to make each of the different colors “available” at all points across the width of the backing). Hall explains that the effective stitch rate run by its machine is a conventional stitch rate multiplied by the number of different colors used to form the pattern. Thus, the more colors used to form the pattern, the greater the effective stitch rate and the slower the machine can be run so as to attain the desired density of the yarn loops. With every additional color used to form the pattern, the speed of production is slowed until ultimately products made with the machine become commercially impractical. Furthermore, the more shifting that occurs, the more yarn that is used, thereby increasing the cost and weight of the product.
Moreover, the greater the stitch rate, the closer the penetrations made in the backing material along the length of the backing. The increased number and proximity of penetrations resulting from the introduction of each additional color into the thread-up can detrimentally impact the integrity of the backing material. In short, there is a limit to the number of different colors that can be used to form the pattern before the machine begins to tear up the backing and thus compromise the integrity of the final product.